Senior Backend Engineer (Python, PostgreSQL, AI Platform)

Ever wanted to take full ownership of a backend and have a real impact on how the product is built? Where you're not just implementing tickets, but making architectural decisions, thinking about scalability, and building systems that can support a growing product? Where you can work closely with the founder, influence technical direction, and eventually help lead another backend engineer? If you enjoy building production-grade backend systems, solving architectural challenges, and taking ownership beyond your individual tasks - we'd love to talk. About the Company Our client is a technology startup building a LinkedIn-based sales technology platform designed to help businesses improve and automate their sales processes. The platform is built as a multi-tenant system and combines modern cloud infrastructure with AI-powered functionality, including integrations with Google's Gemini models. It's a product-focused environment where engineering decisions have a direct impact on the platform and its ability to scale. The Role We're looking for a Senior Backend Engineer who will take full ownership of the backend and effectively act as the technical lead for this area. You'll be responsible for designing and building scalable backend systems, making architectural decisions, and ensuring the platform remains reliable as it grows. You'll work closely with the founder, who has a strong technical background, so this role requires genuine engineering depth and the ability to explain and defend technical decisions. As the team grows, you'll also help guide and collaborate with another backend developer. What You'll Do Backend & Architecture Design, build, and maintain backend services using Python and FastAPI Develop scalable APIs and business logic for a production B2B SaaS platform Design and optimize PostgreSQL databases, data models, migrations, indexes, and queries Make architectural decisions around scalability, reliability, performance, and maintainability Take ownership of backend features from design and implementation through deployment and production Multi-Tenant & Production Systems Build and maintain multi-tenant production systems with strong customer data isolation Design systems that reliably support multiple customers at scale Build robust background jobs with safe handling of retries, duplicates, and partial failures Work with cloud infrastructure and production environments Monitor, troubleshoot, and improve system performance and reliability Handle production incidents, deployments, and third-party service limitations AI & Agentic Workflows Build, maintain, and improve customer-facing agentic workflows Work with AI-powered features as part of a larger production system Design reliable workflows around AI capabilities, data, business logic, and external services Apply engineering judgment to make AI-powered features reliable, predictable, and production-ready Integrations & Data Build and maintain integrations with third-party APIs and data providers Work with OAuth, webhooks, rate limits, and external service dependencies Develop features across signals, campaigns, data enrichment, integrations, and billing Design systems that handle external failures and changing third-party constraints gracefully Production Ownership Own backend systems in production and take responsibility for their reliability Investigate and resolve performance, data, and production issues Work with monitoring, deployments, and infrastructure to keep systems healthy Help investigate customer issues that require engineering involvement Take technical problems from investigation through implementation and production Full-Stack & Product Development Work primarily on the backend while contributing to features across the product when needed Build and ship Next.js / TypeScript screens when a feature requires end-to-end development Collaborate across the product to understand how backend systems connect to the user experience Work directly with the founder on product and technical decisions Ownership & Collaboration Take ownership of technical problems and drive them to resolution Work independently in a fast-moving startup environment Contribute to technical decisions, engineering standards, and system design Balance speed of delivery with long-term reliability and maintainability Communicate clearly with the founder and take responsibility for the systems you build What You Bring 5+ years of experience building and running backend systems in production. Strong Python experience and experience building asynchronous services. Our backend is built with FastAPI . Strong PostgreSQL knowledge, including data modeling, indexes, migrations, and query optimization. Experience with Redis and background processing. Hands-on cloud and infrastructure experience - you've managed environments and debugged live production systems. Real experience with production ownership , including incidents, performance issues, deployments, and data problems. Strong understanding of failure handling - duplicate events, retries, partial failures, outages, and unreliable third-party services. Experience working with multi-tenant systems or similar data-isolation requirements. Enough frontend experience to work comfortably in a Next.js / TypeScript codebase. Good spoken and written English . Comfortable working independently and taking ownership of problems from idea to production. Nice to Have Experience with SaaS or sales technology platforms Experience with AI/LLM integrations, particularly Google Gemini Experience designing multi-tenant architectures from the ground up Previous experience acting as a technical lead or owning a backend domain independently Experience mentoring or guiding other developers Startup experience Frontend experience with modern JavaScript/TypeScript frameworks What You Get Full Backend Ownership: You won't be just another backend developer - you'll own the backend architecture and technical direction. Direct Technical Influence: Work closely with a technical founder and have a real voice in architectural and engineering decisions. Product Ownership: See your technical decisions directly influence a growing product and its users. Modern Technology: Work with Python, PostgreSQL, cloud infrastructure, multi-tenant architecture, and AI-powered functionality. Technical Growth: As the team grows, you'll have the opportunity to take on more technical leadership and guide other engineers. Startup Environment: Fast-moving, direct, and focused on building rather than unnecessary processes and hierarchy. Interested? If you're a strong Python engineer who enjoys owning backend architecture, solving complex production problems, and building products from the ground up, we'd love to hear from you.